This invention relates to a controller for a ramp added to a light duty motor vehicle such as a van, minivan, or sport utility vehicle.
A variety of small motorized scooters have been developed to carry a seated person through areas intended for pedestrian traffic. These scooters are battery powered, ride on either three or four small wheels, and are relatively compact but can be rather heavy because of the battery and electric motor. Powered wheelchairs and scooters are evolving toward each other, making terminology imprecise. One manufacturer avoids the problem and calls its product a “highly maneuverable vehicle.” Some vehicles have wheels at the corners of a rectangle with the driven axle parallel to one side of the rectangle. Other vehicles have wheels at the corners of a diamond, with the driven axle parallel to a diagonal of the diamond. As used herein, “scooter” is intended to be generic to all such vehicles for aiding a person of limited mobility.
Ramp mechanisms are either external or internal to a vehicle. External ramps typically fit under the chassis and are used with vans and larger vehicles. An internal ramp is typically somewhat smaller, fits within the vehicle, and requires a substantial re-working of the body of the vehicle. Physically locating a ramp in an unobtrusive manner is only part of the problem. Vehicles, especially minivans, are becoming extremely sophisticated products yet, outwardly, seem little changed to the average motorist. Underneath the sheet metal is not just a computer but a computer network controlling all aspects of operation; e.g. see U.S. Pat. No. 6,785,595 (Kominami et al.). Actually, there are typically several networks, each with more than one computer, that are relatively separate for safety reasons. For example, the cabin is typically one network, the airbag system another network, and the engine compartment another network. Each network bristles with sensors and actuators.
For the aftermarket installer of ramps for scooters, deciding which wire to cut, if any, is a nightmare. Worse, even from a given manufacturer, the wiring can change from year to year without notice. Worse still, some aspects of the wiring are not disclosed by the manufacturer to avoid claims for liability in the event of a problem. Thus, the problem of coordinating the movements of a powered ramp and an OEM (original equipment manufacturer) powered sliding door can be formidable. Even if solved for a given year and model, the solution may go out of date with model changes. It is desired to have a module that is not only suitable for more than one year but also to be suitable for the minivans from more than one manufacturer.
U.S. Pat. No. 5,308,214 (Crain et al.) discloses an OEM vehicle with an internal wheelchair lift positioned next to a powered sliding door on the side of a minivan. The door opens and closes “automatically” but the coordination of the door with the lift appears to come from an operator. Some limit switches are disclosed for interrupting power to operate the lift until the door is in proper position.
In the prior art, several approaches have been taken to modifying minivans that can be classified according to how invasive they are. A very invasive approach is opening a data bus. If the network is interrupted, responsibility for controlling the vehicle is in the hands of the aftermarket manufacturer. Less invasive is coupling into the data bus, somewhat like eavesdropping on a telephone line. Data circulating on a network is not changed, additional data is provided, either to take over the network or to mislead computers on the network.
U.S. Pat. No. 5,396,158 (Long et al.) discloses a control circuit for a power sliding door that senses, among several other events, whether or not the transmission is in park. If the transmission is not in park, an enable signal is changed to prevent the door from operating. One way an aftermarket manufacturer can fool the control circuit is to make the computer think that the transmission is not in the park position, thereby preventing operation of the door when a ramp is extended or retracted. The '158 patent also discloses a delay function that causes the operation of the sliding door to wait for a period of time, during which a door latch mechanism is permitted to operate. The '158 patent also discloses a “sleep” circuit for shutting down the microprocessor to conserve power.
U.S. Pat. No. 5,684,470 (DeLand et al.) discloses a control circuit for a power sliding door in which a delay circuit automatically turns off the control circuit a predetermined period after an event, such as shutting off the ignition. This prevents children from playing with the power sliding door a short time after the event.
U.S. Pat. No. 6,075,460 (Minissale et al.) discloses an implementation of a single wire, serial data bus network meeting the SAE J1850 protocol standard. The patent also discloses a separate line from a first module to a second module that controls a powered sliding door. This separate line carries a “wake-up ground signal” for enabling, or disabling, the second module. Thus, it is known in the art to use control lines separate from the data bus to which several computers are coupled to form a network.
Many circuits, whether integrated or discrete, have “enable” inputs that turn the circuit on or put the circuit into an active mode. “Wake-up”, “power up”, enable, and the like all mean the same thing: a circuit produces an output appropriate for the input data. “Sleep,” “power-down,” disable, inhibit, all mean the same thing; with power applied, a circuit produces no output, or change in output, regardless of input data.
U.S. Pat. No. 6,091,162 (Williams, Jr., et al.) discloses a network for controlling a sliding door in which a door control module monitors several operating conditions of the vehicle and makes a determination whether or not to carry out a command to open or close the sliding door. These conditions are in addition to conditions monitored by the module issuing the command. In other words, the intelligence is distributed among the modules on a network. There is no single control module as before. The distributed intelligence only makes worse the problem of which wire to cut. It is also disclosed that commands can be delayed or “staggered” to prevent overload.
All modern vehicles have a sleep mode to reduce power consumption by the control networks, at least when the engine is not running. This sleep mode is both blessing and curse. It can be used to trick the OEM system into not operating the sliding door. On the other hand, the sleep mode has the risk of allowing critical events to be missed because the circuit to which a sensor is connected was asleep. If an event is missed, one or more networks can be affected. Most OEM's include default settings to minimize problems. Unfortunately, a default setting may not be optimum under a particular set of circumstances.
Most digital semiconductive devices are voltage devices. This means that, for a single line bus, zero is not nothing, it is a logic level. Logic can be “positive” or “negative.” Positive logic means that a voltage below a first level, near zero, is a logic zero (or “false” or “low”) and a voltage above a second level, higher than the first level, is a logic one (or “true” or “high”). Negative logic is the opposite. For buses having two lines, positive logic, negative logic or differential logic signals can be used.
In digital systems, binary data can only represent one of three things: data, an address, or an instruction. This is the information that is carried on a serial data bus or network as used in modern vehicles. The binary data is sent along the serial bus in a format specified by one organization or another. The J1850 standard mentioned above is from the Society of Automotive Engineers (SAE). Control signals are not on the serial bus, at least not directly. Control information can be passed along a network as an instruction to be executed but the wire, the physical bus itself, cannot also be a control line; see the Minissale et al. patent cited above. Conversely, a control line is not a data bus.
U.S. Pat. No. 6,825,628 (Heigl et al.) discloses a modification to a minivan in which a controller is added to a network coupled to an OEM control module and a door control system. In a second embodiment and in a third embodiment, the door control system is disconnected from the network bus and is coupled to the controller by a separate bus. In the second embodiment, the OEM control module controls a system enable line. In the first and third embodiments, the controller is interposed on the enable line between the OEM control module and the door control system. In all embodiments, the controller is interposed between a key control/switch and the OEM controller. Thus, the modification remains somewhat invasive and requires finding the wires from the key control/switch and a suitable place to separate them from the OEM control module.
As used herein, no distinction is made between the terms “microprocessor” and “microcontroller.” Similarly, a microprocessor can be a single integrated circuit or a “chip set,” having plural integrated circuits. Microprocessors are produced in a variety of capabilities and one of ordinary skill in the art can readily choose an appropriate device. Most manufacturers produce guides for choosing a device.
In view of the foregoing, it is therefore an object of the invention to provide a minimally invasive control system for modifying a minivan to operate an enclosed ramp in coordinated fashion with an OEM powered, sliding door.
Another object of the invention is to provide a module for controlling a sliding ramp, wherein the module did not have to be substantially redesigned for each year, make, and model of vehicle to which the ramp is added.
A further object of the invention is to provide a module for controlling a sliding ramp, wherein the module is compatible with control networks in modern vehicles.
Another object of the invention is to provide a module for controlling a sliding ramp, wherein the module is compatible with non-mechanical entry devices for modern vehicles.
A further object of the invention is to provide a module for controlling a sliding ramp, wherein the module couples into but does not interrupt the serial data bus to which it is coupled.
Another object of the invention is to provide a module for controlling a sliding ramp, wherein the module increases the time that at least certain components are “awake,” thereby increasing reliability of the network as m modified for controlling a ramp.